From DE 32 21 377 C1, a venting and bleeding valve is known, which contains a main valve that is arranged within a valve housing for rapid venting and bleeding of piping, as well as an auxiliary valve arranged in the valve housing for the operating ventilation. Both the main valve and the auxiliary valves are actuated by means of a float as a function of the filling level of a fluid located in the valve housing.
Such venting and bleeding valves are placed in piping systems, generally at high points of the line, and used for starting, for bleeding during operation, and also for safety in case of pipe rupture. During the filling of a piping system, it is possible, for example, using such valves, to remove the air located in the installation from the piping system. The air, which during operation arrives in the pipe due to the entry of air or due to the outgassing of air dissolved in water, and which as a result can be detrimental to the entire piping system, can also be removed during operation by means of such valves. In addition, by means of such valves, the pipes can also be ventilated if, for example, due to a pipe rupture, the rapid outflow of water and, as a result, the formation of low pressure within the pipe occur. However, such venting and bleeding valves in general have a closed structure, so that their operating state cannot be simply determined.